Looks like changes to the Mozilla codebase has recently made it a lot easier to get out of the onbeforeunload alerts: https://bugzilla.mozilla.org/show_bug.cgi?

Looks like changes to the Mozilla codebase has recently made it a lot easier to get out of the onbeforeunload alerts: https://bugzilla.mozilla.org/show_bug.cgi?id=391834 https://bugzilla.mozilla.org/show_bug.cgi?id=391834 The continual resizing one is harder - I guess in the interim the easiest way to get out of it is to open a new window via the command-line and disable Javascript from there.